Improvement in devices for cutting screw-threads



-F. G. ROBINSON.

Improvement in Devices for Cutting Screw-Head s.

Patented June 18, 1872.

v N0.12s,071.

imam:

PATENT OFFICE.

FREDERICK G. ROBINSON, OF PITTSFIELD, MASSACHUSETTS.

IMPRQVEMENT IN DEVICES FOR CUTTING SCREW-THREADS.

Specification forming part of Letters Patent No. 128,071, dated June 18, 1872.

Specification describing a new and Improved Screw Gutter, invented by FREDERICK G. ROBINSON, of Pittsfield, in the county of Berkshire and State of Massachusetts.

The invention consists in an improved screwoutting device, as hereinafter fully described and subsequently pointed out in the claim.

Figure l is a longitudinal sectional elevation of my improved apparatus, and Fig. 2 is a transverse section of Fig. 1 on the line a 01:.

Similar letters of reference indicate corresponding parts.

It is very difficult to start a screw-threadcutting die on the end of a rod or tube by hand and at the same time guide it properly, particularly if the thread is coarse and deep, owing to the great pressure required in the lengthwise direction of the rod. I therefore propose to employ a screw-threaded feeder and guide, consisting of the funnel-shaped device A with an internal screw-threaded part, B, extending from the opening at the large end inward a suitable distance, and at the smaller end 0 suited to be fastened on the shaft or tube by a set-screw, D, either with a bush or not; and I have the socketed stock E, carrying the die F,

provided with a screwthreaded part to screw into B by the turning of the crank for forcing the die on the end of the rod, by which I cause the die to feed onto the rod with certainty, and without other labor than the mere turning of the crank. This contrivance also serves to guide the die correctly without trouble. For adapting the said device A to pipes of different sizes the. hole may be large, and bushes H, with different-sized holes for the pipes of different sizes, may be used.

This apparatus Willbe very useful for blacksmiths, plumbers, 85c.

Having thus described my invention, I claim as new and desire to secure by Letters Patent- As an article of manufacture, a screw-cutter composed of tubular stock E, extern ally-threaded, and having enlarged angular recess for tool F, the hollow surrounding and internallythreaded socket A, and the-bolt-holder D H,

all constructed as described.

FREDERICK G. ROBINSON.

Witnesses: v

JOHN M. TAYLOR, JAMES WILsON. 

